Mangrove in Pakistan are increasing and standing tall – Spatiotemporal assessment (1990-2015)

Introduction

Coastal ecosystems include mixing of fresh and sea water as well as coastlines and adjacent lands. Carbon is stored and captured in mangrove forests, sea grass meadows and inter-tidal salt marshes. The blue carbon is found in soil, sediments and under the vegetation. Oceans and coastal regions capture carbon and reduce the impact of greenhouse gases through sequestration (taking in). Coastal habitats are one of the best conservator of blue carbon, and when these habitats are damaged, large amount of carbon is added back into the atmosphere which results in climate change.

Coasts are affected both by climate change and anthropogenic activity. The global coastal zones are home to over 60% of human population. More than half the world’s population lives within 60 km of the shoreline.

The Sustainable Development Goal (SDG) 14 focuses on the conservation and sustainable use of ocean, seas and marine resources. Oceans contribute towards regulation of the environmental and climate cycle, and also are important economically in terms of fishery. Oceans are facing anthropogenic threats like marine pollution and depletion of natural resources, which enhance the effects of climate change. The Sustainable Development Goal (SDG) 15 focus is to protect, restore and promote sustainable use of terrestrial and fresh water ecosystems, and sustainably manage forests.

Mangrove deforestation emits as much CO2 as Myanmar each year

Mangrove sites in Pakistan

Pakistan’s coastline is 1,050 km long and 40-50 km wide, which is distributed among the Baluchistan (700 km) and Sindh (350 km) province, geopgraphically placed between 24° to 25° N latitude and 61° to 68° E Longitude. In 1958, mangrove forests of Pakistan were declared, “protected forest” under the Pakistan Forest Act 1927 and alongside water channels as “wildlife sanctuaries” in 1977 under the Sindh Wildlife Safety Ordinance of 1972. The human population in and around mangrove forests of Pakistan is approximately 1.2 million, and almost 90% of the population derive their primary income from fishing and its associated activities. Mangrove forests areas are distributed in five distinct geographic pockets: Indus Delta, Sandspit, Sonmiani Khor, Kalmat Khor, and Jiwani (Figure 1).

Fig. 1: Five mangrove sites in Pakistan

Brief methodology – Mangrove cover and change assessment

In the Google Earth Engine (GEE) cloud computing platform, Landsat 30m spatial resolution satellite images were used for generating three land cover classes: Mangrove, Water and Others. Low tide height (preference February to April) 1990, 1995, 2000, 2005, 2010 and 2015 Landsat images were selected for the land cover classification. 70% of the training samples used to train the images through the random forest classification algorithm in GEE while 30% samples were used for accuracy assessment. Approximately 35 samples were taken for each land cover class to train and validate. From 1990 to 2015 at five years intervals, using the conversion (or change) matrix approach, “gross loss”, “gross gain”, and “net change” mangrove cover has been reported and mapped.

Mangrove Monitoring in Google Earth Engine

Spatial-temporal assessment of mangrove cover

Initial findings of this research reveal that over the 25 year period spanning 1990 – 2015, the overall mangrove cover in Pakistan has increased (figure 2). At the national scale over the five sites, mangrove cover has increased from 487 km² in 1990 to 1,279 km² in 2015 with the rate of change 0.04 km²/year.

Figure 2: Mangrove cover assessment based on Landsat 30 m spatial resolution data at five years interval from 1990 to 2015

Pakistan is attempting to mitigate climate change effects through tree plantation initiatives e.g. Green Pakistan Programme, Billion Tree Tsunami in Khyber Pakhtunkhwa province. Particularly in the coastal areas, Pakistan has taken gigantic steps toward conservation of coastal ecosystems through mangrove plantation, community awareness programs, and eco-tourism activities. In the coastal areas, from 2006 onwards, Pakistan has been carrying out annual mangrove plantation campaigns. As an acknowledgment, in 2009, Pakistan received a certificate from Guinness Book of World Records on planting 541,176 mangrove saplings in a single day in Keti Bunder (Indus delta). Indeed, even in later years, mangrove plantation activities continued with more determination to restore the degraded and clear mudflats. National and international Non-Governmental Organizations (NGOs) and local Community-Based Organizations (CBOs) are actively supporting these government initiatives of rehabilitation activities.

Figure 3: Extensive and impressive improvement in mangrove plantation, Hajamro Creek, Indus Delta (24.11620779°N and 67.39126534°E). Photo credits: WWW-Pakistan.

200,000 mangrove planted in Balochistan

Mangrove cover change assessment

In 25 years (1990-2015) over the five mangrove sites, a total 54km² deforestation (loss) and 843km² afforestation (gain) was observed. Out of total deforestation and afforestation, 46km² deforestation and 807km² afforestation was noticed in the Indus Delta.

Figure 4: Spatial extent of mangroves deforestation (loss) and afforestation (gain) in last 25 years (1990-2015).

Future outlook – Pakistan coastal ecosystem mapping and monitoring

• Mangrove forest fragmentation analysis
• Mangrove density (60% tree canopy) mapping and monitoring
• An online web portal for the visualization and dissemination of products
• An online mobile app development for the field data collection
• A detailed field campaign in Jan 2020 over the entire Indus Delta
• Estimation and mapping of carbon emission and sequestration due to deforestation and afforestation, respectively
• A detailed map of mangrove species, algae and salt marshes using Sentinel-2 data

About this post: This is a guest post by Hammad Gilani and Hafiza Iqra Naz

Acknowledgement: The Geo spatial Research and Education Lab (GREL) at Institute of Space Technology (IST), Islamabad, Pakistan; GIS Laboratory at World Wide Fund for Nature (WWF-Pakistan)

Conflicts of Interest: The findings reported stand as scientific study and observations of the author and do not necessarily reflect as the views of author’s organizations.